The invention is concerned with Korean Patent Application Nos. 2001-60680 and 2003-55532.
An artificial diamond (hereinafter referred to as “diamond”) was invented in the 1950s. The diamond, which is known to have the highest hardness out of materials in the earth, has been accordingly used for cutting and grinding tools due to such properties.
Especially, the diamond has been broadly used in a stone processing field where stone such as granite and marble is cut and ground, and in a construction field where a concrete structure is cut and ground.
Typically, a diamond tool comprises segments having diamond particles dispersed thereon and a metal core having the segments fixed thereto.
FIG. 1 illustrates an example of a segment type diamond tool having diamond particles arranged regularly.
The inventors of this invention developed the technology of arranging diamonds regularly in a segment to enhance cutting rate and useful life of a cutting tool, as shown in FIG. 1. Details thereof are disclosed in Korean Patent Application Nos. 2001-60680, and 2002-7568.
As shown in FIG. 1, the segment type diamond tool 1 includes a plurality of segments 11 fixed to a disk-shaped metal core 10, each segment 11 having diamond particles 110 regularly dispersed thereon.
FIG. 2 shows an example of a cutting segment having diamond particles regularly arranged.
As shown in FIG. 2(a), the cutting segment 2 has a plurality of diamond particle layers 210 to 250 arranged at uniform spaces in a thickness direction thereof. The diamond particle layers each have a plurality of particle rows on a cutting surface 20 during cutting. Also, between the diamond particle layers 210 to 250, blank sections 26 to 29 are formed as shown in FIG. 2(b).
In case of cutting a workpiece with the diamond tool having the cutting segment of FIG. 2, diamond particles constituting diamond particle layers 210 to 250 are uniformly protruded in rows 21 and 25 from the cutting surface during cutting. At this time, diamond particle rows 21 and 25 disposed at both the cutting surface and the side of the cutting segment contact the workpiece at both sides and thus sustain biggest load.
Therefore, these diamond particle rows 21 and 25 carry out cutting under more hostile conditions than inside diamond particle rows 22 and 23.
Consequently, with the cutting going on, as illustrated in FIG. 2(c), upper diamond particle rows 21a, 21b, 25a and 25b arranged on the side fall off easily and their underlying diamond particle rows 21c and 25c newly perform cutting. This causes the side of the cutting segment to suffer from rounding wear (hereinafter referred to as “R” wear), also decreasing useful life of the cutting segment. Technologies suggested to reduce such R wear include increasing a concentration of diamond particles arranged at the side, using different-sized particles or using metal binder having higher hardness for the side than that for the inside.
However, the aforesaid conventional technologies disadvantageously entail a complex manufacturing process and do not lead to sufficient reduction in R wear.